Water-Cooled Water-Moderated Nuclear Reactor Core Melt Cooling and Confinement System

Abstract

The invention relates to safety systems for nuclear power plants (NPP), and can be used in the event of reactor vessel and NPP containment failure. The melt cooling and confinement system includes a cone-shaped guide plate installed under the reactor vessel bottom, cantilever girder installed under the guide plate and supporting the same, core catcher installed under the cantilever girder and equipped with cooled cladding in form of a multi-layer vessel for protection of the external heat-exchange wall from dynamic, thermal and chemical impacts, and filler material for melt dilution inside the multi-layer vessel. The said multi-layer vessel contains external and internal metal walls with filler of poorly heat-conductive in relation to the wall material in between. Filler thickness h fil shall meet the following requirement: 0.8 h ext <h fil <1.6 h ext , where h ext is vessel external wall thickness.

1 . Water-cooled water-moderated nuclear reactor core melt cooling and confinement system containing:
 cone-shaped guide plate installed under the reactor vessel bottom,   cantilever girder installed under the guide plate and supporting the same,   core catcher installed under the cantilever girder and equipped with cooled cladding in form of a multi-layer vessel for protection of the external heat-exchange wall from dynamic, thermal and chemical impacts,   and filler material for melt dilution inside the multi-layer vessel,   wherein the said multi-layer vessel contains external and internal metal walls with filler of poorly heat-conductive in relation to the wall material in between,   
       where filler thickness h fil  meets the following requirement:
   0.8 h ext <h fil <1.6 h ext , 
 
       where h ext  is the thickness of the vessel external wall. 
     
     
         2 . A system according to  claim 1 , wherein the internal and external walls are made of steel. 
     
     
         3 . A system according to  claim 1 , wherein the filler with 800 to 1400° C. fusion point is used. 
     
     
         4 . A system according to  claim 1 , wherein concrete layer or ceramic material with a steady heat exchange with the external wall of the multi-layer vessel is used as a filler. 
     
     
         5 . A system according to  claim 1 , wherein bearing ribs are located between the internal and external walls, and the rib thickness (hrib) meets the following criterion:
   0.5 h ext <h rib <h ext      
     
     
         6 . A system according to  claim 5 , wherein bearing ribs pass through the internal wall into the vessel interior volume forming a protective supporting structure. 
     
     
         7 . A system according to  claim 1 , wherein the upper part of the vessel is equipped with a flange, its inner and outer diameters correspond to those of the vessel internal and external walls accordingly. 
     
     
         8 . A system according to  claim 1 , wherein an additional artificial slag layer is installed between the external wall and the filler of the vessel, the slag layer is based on at least one of the following oxides: zirconium oxide, aluminum oxide, ferric oxide, with mass content of the base in the layer not less than 20 wt. %.